Elsewhere across the country, temperatures aren’t expected to rise above freezing, apart from in the capital where 2C is forecast today.
The chilly temperatures would be the coldest spring conditions since March 2018 when the so-called Beast From The East hit the UK.
The Met Office’s weather forecast for tonight says: "Many areas dry, cold and frosty with a mixture of cloud and clear spells.
"Thicker cloud over parts of Scotland leads to some rain here."
Met Office forecaster Matthew Box told MailOnline: “We could see frosty conditions again tonight, with temperatures perhaps reaching similar values of -5C or -6C across parts of the country in England and Wales.”
Forecasters say cold temperatures are due to a cold front - dubbed the Scandinavian Surge - from northern Europe, and say the chill will ease from Monday.
Tomorrow in London lows of 3C are expected and highs of just 6C. There is a low chance of rainfall throughout the day - which will be predominantly cloudy.
On Monday there will be highs of 11 and lows of 3C, which the cloudy and potentially rainy conditions continuing.